1. Field of the Invention
The present invention relates generally to tools for carpet installation, and more particularly, relates to a carpet trimmer
2. Description of the Prior Art
The patent issued to Crain U.S. Pat. No. 4,095,341 (xe2x80x9c""341 patentxe2x80x9d) for carpet trimmer discloses a carpet trimmer comprising a base plate, a post holder underlying the base plate, a blade holder, and a blade retaining member having an ear. The base plate has a base, a wall guide, and an upper wall. In a carpet trimmer manufactured by Crain Cutter Company, Milpitas, Calif., which appears to follow the design of ""341 patent, the upper wall and wall guide are formed by bending upwardly and then downwardly one edge of the base of the blade holder. A first blade holding recess is formed on the inner wall of the wall guide by stamping and by making a notch on the bended edge of the base of the blade holder. The first blade holding recess holds the free cutting end of a blade. A second blade holding recess is formed on the top of the base for holding the body of the blade, whereby the first recess and the second recess define a blade holding area. The blade fits into the blade holding area perfectly without any horizontal moving room. In addition, the blade-retaining member for holding the blade extends into the first recess to hold the free cutting end of the blade.
However, there are several drawbacks in the tool designed according to ""341 patent. The manufacturing of the holding plate is somewhat complex and thus more expensive. It is relatively difficult to make the first recess in the blade holder as disclosed because the manufacturing process involves multiple bending of a metal sheet. Any variation of the material thickness in the metal sheet will cause errors into the locations of any features, i.e., the first recess between the wall guide and the upper wall, which must be stamped into the face of the part itself. Additionally, at the end of the upper wall where the upward bend and downward bend meet, a very small tab is created in order to hold the multiple bends together. The presence of the tab tends to obstruct the flow of the carpet into the blade and also makes the tooling very delicate, which compromises the durability of the stamping die.
In addition, according to the ""341 patent, the removal of the blade from the blade holding area is not with ease because the blade fits into the blade holding area perfectly without any space to move horizontally. It is therefore desirable to manufacture the carpet trimmer in a simpler and less expensive way. In addition, it is desirable for a user to change the blade with ease when dealing with a sharp object.
Therefore, it is an object of the present invention to provide a carpet trimmer, which costs less time and resources to manufacture.
It is another object of the invention to provide a carpet trimmer, which can ride on the carpet more freely within the carpet entry of the carpet trimmer.
It is another object of the invention to provide a carpet trimmer, from which a blade is readily removable with ease.
According to the present invention, a carpet trimmer comprising a base plate. Underlying the base plate is a bottom member with upstanding posts. The base plate is formed with first slots directed at right angles to the working edge of the base plate and the upstanding posts protrude through first slots formed in the base plate. Overlying the base plate is a blade holder, which engages the posts for movement with the bottom member relative to the base plate. The blade holder includes a base and a wall guide being formed by bending one edge of said base downwardly. The base of the blade holder has an indent formed on the bottom surface of the base at the junction with the wall guide. The base overlying said base plate is formed with openings to receive the upstanding posts. The wall guide and the working edge of the base plate define a carpet entry space for receiving an edge of a carpet to be trimmed. The carpet entry space can be adjusted to accommodate carpets of various thicknesses by moving the posts within the first slots formed in the base plate through the simultaneous movement of the bottom member and the blade holder relative to the base plate.
At least one blade is mounted in a blade receiving means formed on the blade holder. The blade projects into the carpet entry space. A securing means on the posts releasably lock the blade holder and the bottom member in an adjusted position relative to the base plate.
According to the invention, the blade receiving means includes a first recess formed on the blade holder for holding the body of the blade and a second recess formed on the inner wall of the guide wall for holding a cutting end of said blade, whereby the first recess, second recess, and the indent on the bottom surface of the base of the blade holder define a blade holding area.
According to the invention, the first recess has a second slot formed at an edge of said first recess away from the wall guide. The blade holding area has a length longer than the length of the body of said blade, whereby the blade may be moved horizontally within said first recess when being removed.
According to the present invention, the second recess is formed by a notched blade supporting strip attached on the inner wall of said wall guide, said inner wall, and said indent on the bottom surface of said base.
According to the invention, the carpet trimmer further comprises a blade-retaining member being disposed above the blade. The blade-retaining member has an ear for receiving the upstanding post and an indent on an edge of the blade-retaining member for seating inside the second open slot of the first recess.
According to the invention, the securing means is above the ear of the blade retaining member to releasably secure the retaining member to the base of the blade holder, whereby the indent of the blade retaining member fitted in the second open slot urges an edge of said blade towards said wall guide and the blade is then secured in the blade holding area.
According to the invention, the carpet trimmer comprises at least one cooperating projection formed on the base plate and a plurality of openings formed on the bottom member. The plurality of the openings are spaced in a direction parallel to the direction of the first slot formed in the base plate, whereby the cooperating projection and spaced openings gauge the desired adjustable movement between the wall guide of the blade holder and the working edge of said base plate, and retain the bottom member in the selected position relative to the base plate.
According to the invention, the carpet trimmer comprises a plurality of individually removable spacer members stacked between the base plate and the base of the blade holder for controlling the distance between the base pate and the base of the blade holder for adjusting the height of the blade relative to the base plate.
According to the invention, the spacer members are formed with vertically aligned openings for receiving the upstanding posts, the movement of the upstanding posts relative to the base plate moves the spacer members therewith relative to the base plate.
According to the invention, the wall means of the base plate is formed with a recess for seating the bottom member therein.
Therefore, the application of the present invention eliminates the need of making multiple bending of a metal sheet during manufacturing of the blade holder. In addition, the removal of the blades will be with ease because of the moving space within the blade holding area. Likewise, the carpet entry point in the trimmer will be smoother because there is no welding point on the junction of multiple bends of the metal sheet that was present in the prior art.